(1) Field of the Invention
The present invention relates to improved apparatus for use in transferring hazardous material between large containers and fume hoods or ventilated workstations, and in particular to an apparatus that is attachable to a fume hood and a large container permitting transfer of hazardous materials between the container and the interior of the fume hood without insertion of any part of the container into the fume hood or exposure of the operator to the hazardous material.
(2) Description of the Prior Art
Fume hoods or vented workstations are used in laboratories and other environments to manipulate materials that might generate noxious or dangerous gases or fumes without releasing the materials or components or fumes therefrom into the work environment. Generally, these fume hoods are comprised of an enclosure or chamber in which materials are handled, and means for drawing air through a front opening in the enclosure. The operator also uses this front opening as the means of access into the enclosure. The enclosure also includes an exhaust opening, frequently communicating with a filter, to remove contaminants from air exhausted from the chamber.
The fume hood is normally comprised of side and top walls, which may be of transparent material, such as PLEXIGLASS™ acrylic plastic sheet, or other clear plastic, a rear wall with an exhaust opening, and a planar bottom wall or floor. The front edges of the top, side and bottom walls may form an operator access opening. A slidable or hinged door may be positioned to cover, or vary the size of, the access opening. Generally, the hood is configured and air vanes are often added, so that air enters the access door and is exhausted through the exhaust opening, with generally laminar airflow being maintained within the chamber to avoid air turbulence that could disturb the materials being manipulated.
Escape of contaminated air from the hood chamber through the access opening into the work environment is prevented by maintaining a pressure differential between the chamber, or hood interior, and the work environment, or hood exterior, so that air continually flows from the hood exterior through the access opening into the hood interior. A sufficient air velocity at the access opening, known as the “face velocity,” must be maintained to prevent contaminated air from escaping.
Contaminated air is exhausted from a fume hood through an exhaust conduit that includes a vacuum source to draw the air through the exhaust conduit. Generally, this vacuum source is comprised of an exhaust fan positioned within the conduit, and an electric motor to turn the fan. The gas may be exhausted to the exterior environment when toxic contaminants are not present. In many instances, however, the air will be conveyed through a filter, such as a HEPA filter, to remove contaminants from the air.
When working with hazardous or toxic material, there is frequently a need to transfer portions of the contents of a container into the interior of a fume hood or workstation without releasing any of the contents into the surrounding environment. Some of these containers, which may be carboys, drums, or the like, are quite large and difficult to maneuver. Therefore, placement of one or more of these containers into a fume hood to prevent escape of hazardous materials into the surrounding environment, as well as their subsequent removal, and the insertion or transfer of materials to or from these containers, can be difficult, if not impossible.
In order to address this need, U.S. Pat. No. 6,431,975 to Ryan, issued Aug. 13, 2002, and incorporated herein by reference in its entirety, describes an apparatus and method for transferring hazardous materials between a large container and a fume hood chamber.
Generally, the Ryan apparatus is comprised of an enclosure having walls that define a chamber that includes at least one container-receiving opening in the floor of the enclosure. The enclosure is supported so that a large container having a top opening through which material can be added to, or removed from, can be positioned beneath the enclosure and then raised upwardly, so that the upper section of the container projects through the opening and into the enclosure.
The operator can then open the container from within the enclosure, remove or add material, and then close the container. The container is then lowered to separate the container from the enclosure. As a result, the opening into the container is at all times within the fume hood enclosure when the container is open, thereby preventing hazardous materials from escaping from outside the hood enclosure. As used herein, the term “hazardous” is broadly intended to include all materials, whether in powder, liquid or gaseous form, where escape beyond a confined area is undesirable, and the term “container” is intended to include all containers for such materials.
While the Ryan apparatus is effective in transferring materials without exposing the operator, there is still a need for an apparatus that will achieve this desired result using a fume hood of a more conventional construction, without the need for one or more large holes in the floor of the fume hood.